I have just received from fairly new client a 2011/12 coding notice showing an unexplained adjustment for underpaid tax. Having spoken to HMRC this is apparently from 2003/04, which should have been coded in 2005/06 but "got lost". Do I have any claim to get this adjustment removed? I appreciate that the tax was and is still due but as far as my client is concerned they have been completing Returns for years and everything was fine.
Has anyone come across this before?